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    <title>Document</title>
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<body>
    <div id="ganfan_id">
        我能去你家吃饭吗？就一碗！！
    </div>

    <script>
        $(document).ready(function() {
            // $("#ganfan_id")等同于document.getElementById("ganfan_id");
            $("#ganfan_id").html("<b><i>我能去你家吃饭吗？就一碗！！</i></b>");

            $("#ganfan_id").append("不行！！");

            $("#ganfan_id").after("不行！！！！！");
        });
    </script>
</body>

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